Pipe valve is a mechanism for opening, closing, or controlling the flow of medium within pipe.
There are many types of pipe valves, and there are a variety of classification methods. If divided by purpose, valves can be divided into cut-off valve, check valve, distribution valve, etc.. If divided by pressure, valves can be divided into vacuum valve (working pressure is less than the standard atmospheric pressure), low pressure valve (PN ≤ 1.6MPa), medium pressure valve (PN = 2.5-6.4MPa) and high pressure valve (PN = 10-80MPa). If divided by the drive, valves can be divided into manual valve, power drive valve and automatic valve. There are also different classification methods, such as divided by temperature or material.
Gate valve is a gate shutter, the valve seat and the valve plate is equal, the valve plate vertical up-and-down move through the hand wheel to cut off or open the pipeline, and can adjust the opening ratio of the pipeline. Due to the characteristics of the gate, in general application, the gate valve is fully open or fully closed adjustment, less for the flow regulation. But the gate valve has advantages of good sealing performance and easy maintenance. The valve body of the shut-off valve falls vertically on the base, and the valve seat is parallel to the center line of the pipe. The fluid flow in "S" in valve body, and the fluid resistance is large. The shut-off valve is generally used for flow regulation and is easy to manufacture and maintenance, but it is easy to leak when close, and its sealing is not as good as the gate valve.
In the long-distance transmission pipeline laying, valves must be installed along the line, and the spacing should not exceed 32km, if the pipeline through the sparsely populated areas that can be properly relaxed restrictions. Along the underground oil pipelines, both ends of the pipeline when crossing and spanning in large areas of rivers, lakes, reservoirs and towns, and densely populated areas, or required according to the topographic condition, need to set the valve. The location of the shut-off valve should not be affected by geological hazards and floods, and to meet the convenience of transportation, easy maintenance, it should be set up protection facilities.
